The present invention relates to the art of key design and, in particular, to a new key designed for use in a cylinder lock of the type which contain at least two rows of tumbler pins which must be displaced to form the locking combination.
In the field of locking mechanisms constant efforts are made to improve locking combination characteristics, such as operability and security against unwanted openings. To this end, there has been developed in the area of cylinder locks the combination of more than one linear row of tumbler pins so that the proper locking combination may only be effected by the simultaneous displacement of more than one row of tumbler pins to their respective correct locking combination positions. Consequently, in order to achieve this simultaneous displacement, a key must be used which has more than one edge formed with the appropriate projections and depressions to move the tumbler pins to their proper locking combination positions.
Multiple-edge keys designed to operate cylinder locks having multiple rows of tumbler pins present certain problems in both fabrication and especially in reproduction. As is appreciated from simple observation of any key, the projections and depressions formed on the operative edge are of different magnitude. Thus, when two or more operating edges are arranged side by side, not only are the projections and depressions of the respective edges noncoincidental, but the magnitudes of the parallel projections and depressions will also be incongruous. This structural characteristic prevents normal cutting of a straight edge of a blank key blade since such cutting, usually performed with a grinding wheel, is indiscriminate with regard to lateral distance transverse to the operative edge. As a result, use of multiple-edge keys and, consequently, cylinder locks of the type requiring multiple-edge keys are severely limited.
It is the object of the present invention to overcome the difficulties described above and others associated with use of cylinder locks having more than one row of tumbler pins which must be displaced to effect the locking combination.